1. Field of the Invention
This invention relates to sonobuoy deployment apparatus and more particularly to automatic parachute ejection and communication float deployment.
2. Brief Statement of the Prior Art
Sonobuoys are devices adapted to be dropped by parachute from an aircraft, are equipped with a hydrophone for detecting underwater sounds in an active or passive manner and transducing them to electrical signals and have an automatic radio transmitter for transmitting the detected signals to air and surface craft. The aforedescribed components are all initially contained in a sonobuoy cylindrical outer casing. After the sonobuoy is dropped or launched from the aircraft the parachute is deployed to provide a controlled descent to the water surface, the parachute shroud line ends being releasably attached inside the outer casing. After the sonobuoy enters the water, the shroud line ends are ejected from the casing and a communication float having an antenna, radio frequency transmitter, logic controls, and power supply exits the outer casing and rises to the water surface. The hydrophone is deployed at a controlled depth below the water surface for underwater sound detection.
In one previous system, the shroud line end ejection and float exit are effected by a bendable retaining plate releasably mounted near the casing one end. An inflatable float bag of a flexible material such as a heavy plastic is positioned inside the casing and after the sonobuoy is in the water the bag is inflated as from a pressurized canister. When the bag pressure is sufficiently high, a bending force is applied to the plate causing it to buckle and be ejected from the outer casing, whereupon the shroud line ends are ejected and the bag exits the casing and rises to the water surface. This system is relatively expensive owing to the cost of the inflatable bag and pressurized cartridge, has a relatively low shelf life due to gradual pressure loss from the cartridge, and requires differently sized and/or configured plates and cartridges for different size buoys.